In the conventional technique for injecting a liquid medicine into a patient with a needle, the pain experienced by the patient is increased when more than a single puncturing thereof is needed, e.g., where liquid medicine is injected into a plurality of the affected parts in a predetermined area and where the affected part to be injected is rather large.
In FIGS. 1A to 1C there is shown one type of conventional structure for injecting liquid medicine in which there is provided a set of double needles composed of an inner needle 1 and an outer needle 2 respectively having bevels 1a and 2a and being respectively fixed to bases 3 and 4. FIG. 1A shows the construction of a set of double needles in which the inner needle 1 is adapted to be inserted into the outer needle 2 while FIGS. 1B and 1C show the inner and outer needles 1 and 2 separated from one another.
According to the conventional set of double needles formed per FIG. 1A for injecting liquid medicine, the double needles are punctured together into a human body, to reach the part thereof that is to be medicated by injected liquid medicine. Liquid medicine is thereafter injected into the affected part through the narrower inner needle 1 from the base 3 by which a syringe (not shown) containing the liquid medicine therein is connected. On the other hand, a relatively large amount of liquid medicine may be injected in a short period where a syringe (not shown) containing that amount of the liquid medicine is connected to the base 4 of the wide bore outer needle 2 from which the inner needle 1 is removed as shown in FIG. 1B.
There is, however, a need for a double needle structure where the doctor administering the medicine can exercise precise control at all time during the injecting activity and unintentional relative motions between the inner and outer needles are avoided.